Method of and apparatus for making aneroids



April 11, 1939. P. KOLLSMAN A METHOD OF AND APPARATUS FOR MAKING ANEROIDS Original Filed May 15. 1933 I ENTOR ATTORNEY Patented Apr. 11, 1939 METHOD OF AND APPARATUS FdR MAKING I ANEROIDS Paul Kollaman, Stamford, Conn.

Application May 15, 1933, Serial No. 671,080 Renewed March 12, 1938 34 Claim.

This invention relates to methods of and apparatus for making devices such as pressure sensitive boxes.

One object of the invention is the provision of an improved method of constructing sealed pressure sensitive boxes, and more specifically, the invention contemplates the assembling of the walls of the boxes and evacuation of the latter in one continuous process.

Another object of the invention is to furnish an improved method of making pressure sensitive devices, whereby a plurality of pressure sensitive boxes or aneroids can be individually assembled, evacuated andinterconnected in a unit, simultaneously, or in acontinuous manner.

Another object of the invention is to provide a method of manufacturing aneroid boxes whereby the same are heat treated while being assembled.

Another object of the invention is the provision of an improved apparatus for constructing pressure sensitive boxes according to the method referred to, and which apparatus shall have few and simple parts, be inexpensive to manufacture, convenient, expeditious, durable, reliable and efiicient in use.

All of the features hereinafter described, or a lesser number thereof may be used in practising the invention, and the various steps of the process may be practised in various orders.

Other objects and advantages of the invention wile;i become apparent as the specification proce s.

With the aforesaid objects in view, the invention consists in the novel combinations and warrangements of parts hereinafter described in their preferred embodiments, pointed out in the subjoined claims, and illustrated in the annexed drawing, wherein like parts are designated by the same reference characters throughout the several views.

This application is a continuation in part of application Serial N0. 433,882, filed March '7, 1930 now Patent Number 1,930,899. In the drawing:

Flgure l is a view in vertical section of a device embodying the invention and showing a typical use thereof in practising the method, a portion of the device being a section on line 1-I of Fi 2.

Fig. 2 .is a top plan view of the device with the heating bath removed, and parts broken away to show the internal construction.

Fig. 3 is a plan view of a guiding and supporting element of the device.

Fig. 4 is an edge view of a device produced according to the invention.

Fig. 5 is a plan view of a modified aneroid embodying the invention.

Fig. 6 is a cross sectional view thereof, taken on '5 line 6-6 of Fig. 5.

The advantages of the invention when outlined are best realized when all of its features and instrumentalities are combined in one and the same structure, but, useful devices may be produced embodying less than the whole.

It will be obvious to those skilled in the art to which the invention appertains, that the same may'be incorporated in several different constructions. The accompanying drawing, therefore, is submitted merely as showing the preferred exemplification of the invention.

Generally described, the invention provides a method and apparatus for the manufacture of pressure sensitive boxes. The latter have flexible walls and are sealed with a suitable internal pressure, which approaches a vacuum in the case of aneroids. Such aneroids may be furnished with internal or external springs for supporting the elastic walls, or may be free of such springs. To assure accuracy and uniformity in the readings' caused by the aneroids, as well as a high degree of sensitivity thereof, over a considerable range of pressures, the aneroids are made of a very thin sheet metal of fine quality, such as phosphor bronze, and the elastic walls may be reenforced as by being corrugated in any suitable manner. Generally, these aneroids are made of a pair of cup shaped elements soldered together, as along annular flanges. The joint so produced must not only be perfectly tight and must not develop an opening after repeated deformation of the aneroid, but the joint must not create strains or dis-- tortions in the aneroid. So important is this, that the aneroid is ordinarily subjected to a lengthy heat treatment at a low temperature to eliminate strains. Usually the aneroids have center posts connected thereto for transmitting motion caused by the aneroid, or for mounting the latter, or for interconnecting a plurality of 45 aneroids. Such center posts ought ,to be fairly accurately alined with the aneroids, and so secured thereto as to avoid the creation of undue strains in the aneroids. Moreover, where a unit of a plurality of alined aneroids is employed in an 50 instrument, the same must be positioned in close proximity to each other so as to occupy as little space as possible in the instrument, and hence the axial interconnection of the aneroids has been a difilcult thing to accomplish.

By this invention, the cup elements, and also the center posts, if desired, of one or more aneroids are maintained in accurate relation to each other, and the aneroids are evacuated, heated in part but preferably throughout, and sealed, and the center posts secured, all in one or a continuous operation, which may involve soldering of the joints. Moreover, the formation of the joint in the aneroid is performed with the pressure external of the aneroid being substantially equal to that of the evacuated interior of the aneroid, so that the cup elements or walls are not greatly deformed while the joint is being made. One possible simplified manner of creating the joints is by initially treating the parts thereof with solder to tin the same so that when the parts are subsequently assembled and heated, the joints are directly produced.

Referring in detail to the drawing, l8 denotes a device embodying the invention and whereby the novel method may be practised. Said device may include any heating means such as a heated liquid bath including a container II that may have molten lead I2 therein.

Removably immersed in the lead bath is a device I3 that may include a receptacle l4 and a cover l5 therefor, made of any desired heat conducting material that will not be attacked by the bath l2. For instance, the device 13 may consist of aluminum. The receptacle l4 may be of generally cylindrical internal shape to conform to the aneroid unit l6 that may be constructed therein. Thus said receptacle may have a bottom wall l1 and a circular side wall I8, the latter having any removable sealing engagement with the cover. The sealing engagement may be provided by means of an annular seating groove I! in the wall l8, the cover having a corresponding annular tongue 20 slidably fltted in said groove. For creating a vacuum in the device l3, a tube 2| may be secured to a central boss 22 of the cover, said tube communicating with the interior of the device 13, and a connection such as armored hose 23 extending from said tube to a suitable suction pump, (not shown). Thetube 2| may be sufllciently long so as not to cause an undue amount of heat to be transmitted to the hose. When the suction is applied, the cover I5 is drawn into tight engagement with the receptacle l4 to make a substantially air tight joint at is, 20, and the capacity of the pump may be sufficient so that any slight leakage that may occur will be insufficient to materially affect the degree of vacuum in the device l3. Moreover, since the device is immersed in the lead bath, the latter will afiord an additional air seal, while the lead itself will be unable to enter said device.

The receptacle I l may have annular means such as a shoulder 24 for exerting pressure on an aneroid at the region of the joint. If an aneroid such as 25 includes side walls or cup shaped elements 26, having annular flanges 21- which are to be united along a surface 28 therebetween, the shoulder 24 may be arranged to conform to the external shape of a flange 21 of the lower aneroid wall. A small clearance may be provided between the outer edges of the flanges 21 and the internal cylindrical surface 29 of the receptacle l4. The wall l1 may have an internal projection 30 to afford a seat for the flat central region 3| of the adjacent aneroid wall to which region a center post may subsequently be secured. The corrugated part 32 of the adjacent aneroid wall between the region 3| and the flange 21 may be received in the annular recess between the shoulder 24 and the central projection 38. The seat afforded by the shoulder 24'may be at a higher elevation than that of the projection 38 to conform to the shape of the lower aneroid wall 26. The companion upper aneroid wall 26 has its flange 21 resting on that of the lower aneroid wall, so that pressure exerted on said flanges for uniting the same is taken up by the means or shoulder 24.

If a plurality of aneroids are to be simultaneously assembled, an intermediate seating and pressure applying means 33 may be provided, to be disposed between the aneroids which in the unassembled condition may be denoted A and B. The means 33 may be in the nature of a plate or disc 34' having on its opposite faces alined annular seating and pressure applying means such as flanges 35, 36 which may afford seats corresponding to those of the shoulder 24. The annular means 35, 36 may be removably fltted to the cylindrical surface 29, with flange 35 resting on the flanges 21 of the aneroid A, and the flange 36 affording a continuous support for flanges 21 of the aneroid B. Openings such as 31 in the disc 34 may intercommunicate the spaces on opposite sides of the disc for assuring a balance of vacuum. If the aneroids are to be axially interconnected by a post 38, the means 33 may be diametrally split as along a line 39 into two equal and similar halves, and an opening 48 centrally formed in the disc 34, whereby the post 38 is received with its flanges 4| overlying the opposite faces of'the split disc adjacent to the hole 40. In this manner the center post 38 is adequately held by the means 33 while being inserted therewith into the receptacle l4.

For seating engagement with the flanges 21 of the aneroid B on a side thereof opposite to the means 33, a means 42 may be provided which may have a plate or disc 43 and an annular seating element or flange 44 on one side thereof, removably fitted in the cylindrical wall 23 and pro- :lecting downward in opposite relation to flanges 36 and shoulder 24. For axially releasably holding a center post 45 having an end anchor plate 46 to be secured to an adjacent wall of the aneroid B, the plate 43 may have an opening 41 extending therethrough to receive the center post and permit the latter to extend with a suitable clearance into the tube 2 l If desired, the plate 43 may have a boss 48 about said opening 41' for seating engagement with the anchor plate 46.

It will be noted that the means 33, 42 and I4 cooperate to provide compartments for the reception of aneroids A and B, and for maintaining the parts thereof and the center posts in alinement with each other, while exerting a substantially continuous pressure on the flanges 21 and simultaneously pressing the center posts against their coacting elastic aneroid walls. Because of the elasticity of these walls, an inherently adjustable contact engagement is aflorded, whereby the contacting parts of the unit Ii, which have been initially tinned, become united upon being heated.

In order to assure the uniform evacuation of air from all parts of the device l3, a plurality of recesses 53 may be formed in the wall I 8, which recesses may extend into the shoulder 24 as at 54. Pressure equalizing openings 55, 56 may also be provided in flange 35 and in plate 43, if desired. However, these various openings and passages may be omitted, since there will always be sumcient leakage to assure a uniform evacuation of air throughout the device [3.

If only one aneroid is to be constructed, the means It may or may not be used, and a center post such as 45 connected to either of the aneroids A or B. x

- Having described the apparatus for practising the method, the latter will now be briefly described. The separate walls 26 of aneroid A are flrst placed in the receptacle l4, so as to rest on abutment 30. Then the means 23 is assembled about the center post 38 and inserted with the latter into the receptacle so as to rest on aneroid A at center post 38. Next the separate walls of aneroid B are inserted into the receptacle to rest on the center post 38, and the member 42 with center post 45 therein is placed in the receptacle with the member 42 carried by the anchor plate 46. Finally, the cover I is applied to the receptacle l4, causing the springs to exert pressure whereby the walls 26 of the aneroids A and B are deformed to any desired degree so.that flanges 35, 36 and 44 and the shoulder 24 come into contact with the aneroid flanges 21 and press the same snugly together, while the pressure on the center posts is increased. Then suction is applied to the device l3, drawing the cover l5 snugly down upon the receptacle I4 and substantially fully evacuating air from the said device so that the aneroids,

when sealed, will have the desired vacua therein. Now the device i3 is inserted into the heated liquid bath l2, which aids in sealing the device and which quickly and evenly heats the various parts including the aneroid walls so as to cause the tinned surfaces at the desired joints to fuse into engagement with each other to produce the unit i6. Immersion in the lead bath may be continued for such time as to obtain the requisite heat treatment of the aneroids, and since such treatment may occur at a substantially higher temperature than would be otherwise possible, the time element may be considerably reduced. During this heat treatment'the metallic parts of the unit l6 may adjust themselves to avoid ultimate strains. Since there are no difierences of air pressure in the device l3, there will be nothing to cause a flow or removal of solder from the joints, nor will the solder become oxidized as there is a substantial vacuum maintained. When the process is ,completed, the suction may be cut oif, and the device l3 removed from the bath and opened. The

member 42 can then be removed, and the split element 33 withdrawn, so that there is a complete heat treated, evacuated, reliably sealed and new rately alined aneroid unit It.

By subjecting the flanges 21 to a relatively low pressure before the joints therebetween are completed, a substantially fully evacuated aneroid can be readily produced, although there is ordinarily suflicient roughness between the flanges to permit full evacuation regardless of the pressure on the flanges. I

If desired, the unit it can be removed as soon as the joints are made. and then heat treated in an oven at such lower temperature, and for such length of time as may be required.

As soon as the suction is cut off, the aneroid will contract under normal atmospheric pressure.

However, such contraction will be comparatively small because the walls of the aneroid have been somewhat deformed toward each other by axial pressure while the constructionof the unit l6 was in progress. The aneroid unit may thus have its Joints constructed in a position of deformation of the elastic walls which may correspond to an average of the performance of the unit between high 5 and low altitudes. thus aflording superior uniformity in operation. Thus the aneroid is constructed at a temperature and under a pressure both sufllciently low not to substantially distort or In Figs. 5 and 6 "is shown a modified pressure I sensitive box or aneroid 60 which can be made according to the method and with the apparatus hereinbefore described, or in any other desired manner. This aneroid is characterized in that its elastic walls ii are so shaped as to increase the range of deformation of the aneroid, and yet to keep its hysteresis down to a minimum. Whereas aneroids have heretofore been provided with concentriccorrugations in the elastic walls thereof, according to my invention the corrugations may be arranged to lie in generally radial paths.- A preferred form is to provide the walls 6| with spiral corrugations 62 of a suitable curvature. These corrugations may extend from the annular region 63 of the aneroid, adjacent to the flanges 64,-to the central region 65 thereof, into which the corrugations may merge. of the corrugations may lie at'angles of 45 degrees with the corresponding tangents to the aneroid, and the corrugations may gradually diminish in width and depth toward the central region of the aneroid. The walls 6| may be of metal of uniform thickness throughout, if desired, and all elastic parts of said walls will deform proportionately in response to external pressure changes. The maximum depth of the corrugations may be substantially the same as that of the usual cir- The outer portions 66 generally inwardly concaved to a suificient degree so as not to become convex even at the highest altitudes at which the aneroid may be used. The number of the corrugations may in general be governed by the thickness, nature and workability of the metal.

I claim:

' 1. The method of constructing a circular pressure sensitive box having elastic walls, which includes continuously autogenously sealing said walls together along said circular edge while maintaining the interior of the box under a substantial vacuum, and simultaneously autogenously connecting a center post to one of said walls.

2. The method of constructing an aneroid hav ing elastic walls which includes heating and sealing said walls throughout in a substantially evacuated chamber .and securing a center post to one of said walls while the same are hot.

3. The method of constructing an aneroid having elastic walls, which includes positioning said walls in contact with each other, pressing a cenment with each other to form aneroid elements, axially disposing a center post between adJacent walls of the diiferent elements with the center post being pressed against said walls, evacuating the region around said walls for producing evacuated aneroids, heating said walls and center post and causing the same to be autogenously united to obtain said unit.

5. A device for constructing aneroids including a receptacle, a removable cover therefor, means communicating with the receptacle for evacuating the same, means in the receptacle for supporting a plurality of aneroid walls, and other means for pressing said walls together.

6. A device for making aneroids including a closed receptacle having annular elements for seating therebetween the flanges of aneroid walls, one of said elements being movable, means for actuating the movable elements to cause the flanges to be pressed together, and means connected to said receptacle for evacuating the same.

'7. A device for making aneroids including a closed receptacle having annular elements for seating therebetween the flanges of aneroid walls, one of said elements being movable, means for actuating the movable elements to cause the flanges to be pressed together, one of said elements having a portion for holding a center post and pressing the same against an aneroid wall,

and means for substantially evacuating the receptacle.

8. A device for making an aneroid unit having a plurality of annularly flanged aneroids interconnected by a center post, including a closed receptacle having oppomd annular seating elements, a third element between said seating elements. said-third element having annular seats on opposite sides thereof for coacting with the respective adjacent seating elements to press together the flanges of the aneroid walls, and the third element having means for holding a center post between the aneroids.

9. A device for constructing aneroids comprising a receptacle adapted to be heated and including means for pressing together a plurality of separate aneroid walls, means for alining a center post with said walls and adapted for pressing the same against one of said walls, and means connected to the receptacle for evacuating gases therefrom, said receptacle having a removable cover for opening the same and being adapted to be closed substantially gas tight.

10. The method of constructing an aneroid having elastic walls and a relatively rigid peripheral joint, including assembling said walls in a chamber, constantly applying pressure to the aneroid including uniformly peripherally pressing together the joint parts and centrally elastically deforming said walls toward each other, and simultaneously evacuating .all gases from the chamber including the space between the aneroid walls and applying heat to said chamber to cause the joint parts to be autogenously united.

11. The method of constructing an aneroid having elastic walls and a peripheral Joint, and centrally connecting a center post to one of said walls, including assembling said walls and center post in a chamber, constantly pressing the aneroid walls toward each other and said center post toward an adiacent wall of the aneroid, including exerting a continuous peripheral pressure on the joint and causing the aneroid walls to be elastically deformed toward each other, with the deformation in one of said walls caused by the pressure of the center post thereon, and simultaneously evacuating all gases from said chamber including the space between the aneroid walls, heating said chamber while evacuated to cause the joint to be autogenously closed and the center post to be autogenously connected to the aneroid.

12. A device for constructing an aneroid having elastic walls and a peripheral autogenously closed joint, and a center post connected to one of said walls, including means for alining the center post with said walls, and pressing means including means for exerting a pressure on the center post toward the wall, and means for peripherally pressing said walls toward each other.

13. A device for constructing an aneroid including a receptacle adapted to be heated, said receptacle having a removable cover for sealing the same, said receptacle having means for maintaining the aneroid walls in alinement with each other and for pressing the walls towards each other, and means communicating with the re-' ceptacle for exhausting gases therefrom, said receptacle being otherwise closed.

14. A device for making aneroids including a receptacle adapted to be heated, said receptacle being adapted to maintain the walls of the aneroid pressed toward each other, said recep-- tacle having means for removably holding and pressing a center post against one of said walls, said receptacle having a removable cover, and means communicating with the receptacle for evacuating gases therefrom.

15. The method of constructing an aneroid having walls concaved toward each other, which includes assembling the initially separate walls of the aneroid and maintaining said walls separate until the same are inter-connected by solder, and simultaneously evacuating gases between the walls and uniformly heating and peripherally soldering said walls at a'relatively low temperature to avoid distortion of said walls, while relatively uniformly pressing the pheral portions of the walls toward each other to produce a uniform aneroid wherein the stresses, if any, are balanced.

16. The method of making an aneroid having walls concaved toward each other, including assembling the separate symmetrical walls of the aneroid and maintaining said walls separate of each other, evacuating the gases between said walls, and uniformly heating the walls and peripherally soldering the same, at a relatively low temperature, and simultaneously centrally axially pressing the walls toward each other to cause uniform elastic deformation of the walls during the soldering operation.

17. The method of making an aneroid having walls concaved toward each other, including assembling the separate symmetrical walls of the aneroid and maintaining said walls relatively disunited until completely peripherally autogenously united, evacuating gases between walls, and relatively uniformly heating said walls at a relatively low temperature for the autogenous connection, pressing peripheral portions of said walls toward each other and central portions of said walls toward each other to produce uniform elastic deformation in the walls, and peripherally autogenously uniting said'walls.

18. The method of making an aneroid having relatively symmetrically corrugated walls concaved toward each other with the corrugations extending toward the center of the aneroid, including assembling and maintaining said walls comparatively separate of each other, relatively uniformly heating said walls at a relatively low temperature, pressing said walls toward each other so as to bring the peripheral portions of'the walls into close contact with each other, the pressure being centrally exerted to cause a uniform concave elastic deformation of a wall, and autogenously peripherally uniting the said separate walls at said temperature and under said pressure.

19. The method of peripherally soldering and producing an evacuated aneroid having initially separate concave walls, including disposing said walls in assembled relation in a closed chamber, mechanically maintaining the walls uniformly elastically deformed toward each other, evacuating gases in said chamber, and heating said chamber at a relatively low temperature to heat said walls and peripherally soldering said walls together to produce the aneroid.

20. The method of making an aneroid and connecting a center post thereto including assembling said walls while relatively free of each other and aligning a center post with one of the walls, peripherally pressing said walls toward each other and pressing the center post toward its wall to produce an elastic deformation therein while centrally exerting an inward pressure on the other wall to produce a like elastic deformation therein, and autogenously peripherally uniting said walls and said center post to its wall, including'heating said walls at a relatively low' temperature.

21. In a vacuum device for making an aneroid unit having a plurality of annularly Jointed aneroids interconnected by a center post, means having opposed seating elements, a second means located generally between said seating elements, said second means having annular seats at opposite sides thereof, said annular seats coacting with said seating elements to annularly press the walls of the respective aneroids toward each other and to press the different aneroids toward each other, and the second means including means for holding a center post between the aneroids.

22. The method of making an annularly jointed aneroid, including yieldably peripherally pressing the walls 01' the aneroid toward each other, simultaneously pressing a center piece against a wall, so as to elastically deform without distorting the same, and finally simultaneously autogenously uniting said walls and center piece.

23. A device for use in soldering separate wall elements to produce an aneroid, including means for peripherally engaging and pressing the wall elements toward each other, means for causing central engagement and pressure on the wall elements toward each other, and a unitary means for actuating both of the first named means, whereby the aneroid can be peripherally soldered with the wall elements in predetermined relation to each other. I

24. A device for use in soldering separate elastic wall elements to produce an aneroid, including means for peripherally ensuing and pressing the wall elements toward each other, and means for causing central engagement and pressure on the wall elements toward each other, the first mentioned means being resilient to permit exertion of the peripheral pressure as solder between the wall elements is melted. the second mentioned means coacting with the first mentioned means for exerting 'a prJssure to cause the wallelements to deform toward each other during the soldering operatiom.

'25. Adevioe foruseinsoldcrlngscpsrsteeiastic wall elements and a center post to at least one of them to produce a mountable diaphragm box, including means -for peripherally engaging and pressing the wall elements toward each other, means for engaging and pressing a center post against one wall and for causing central pressure on the other wall inward of the box, and a unitary means for actuating both of the first mentioned means, whereby said wall elements and center post can be soldered with the wall elements elastically deformed toward each other.

26. A device including a heated liquid metallic bath, a soldering chamber therein having a removable cover, said cover and said chamber having male and female slidably interengaging annular portions afiording a joint sufilciently tight to prevent a flow of liquid into the chamber but not sufilciently tight to prevent a flow of gas into the chamber, said interengaging portions being relatively freely movable away fromeachother, said liquid constituting a seal to prevent a flow of gas into the chamber at the cover, and controllable gas evacuating means connected to the chamber and producing a low gas pressure therein to cause the chamber and cover to maintain the said annular portions strongly interengaged while said low gas pressure is maintained in the chamber.

27. A device including a container comprising a container body, a removable cover therefor en gageable with the container body, the container having means for peripherally engaging an aneroid to marginally press the walls thereof together for a soldering operation, the cover coacting with said means to actuate the same in the engaged position of the cover on the container body, the cover affording a closure for the container body so that the latter can be immersed in a heating liquid.

28. A device including means for. peripherally engaging the walls of an aneroid and pressing the same together for a soldering operation, a container for said means, said container having a.

container body and a removable cover therefor, the latter and the container body having male and female seating slidable engagement with each other, said means being clamped between the v container body and cover to exert said pressure on the walls of the aneroid, a chamber having a molten heating liquid in which said container is immersed, and means for evacuating gases from said container connected thereto to remove gases from between the aneroid walls and to cause the cover to be maintained in snug engagement with the container body in response to the reduced pressure in the container.

29. The method of constructing an aneroid capsule comprising the steps of positioning separately in register a plurality of sets of aneroid capsule elements, mounting said sets simultaneously in a container and applying pressure simultaneously thereto, evacuating the said container and said sets of registered aneroid capsule elements and heating the said capsule elements to a temperature sumcient to cause autogenous union between the several members of the respective sets while evacuated, cooling the said sets below the autogenous union temperature and thereafter relieving the vacuum within said container.

30. That method of making an aneroid capsule which comprises the steps of applying solder to the rim of a formed diaphragm cup; assembling and placing into an exhaustible container said cup and a closure member adapted to complete said cup into a capsule, said closure member being pressed against the rim portion of said cup by a force applied at the rim portion, the force being of such magnitude as not to eflect cold binding of the tin at the rim portion; evacuating said container; and heating said container to a temperature above the melting point of said solder, whereby the cup and closure member are evenly heated and connected and internal stress in the completed capsule is obviated.

31. That method of making an aneroid capsule which comprises the steps of applying solder to the rim of a formed diaphragm cup; assembling and placing into an exhaustible container said cup and a closure member adapted to complete said cup into a capsule, said closure member being pressed against the rim portion of said cup by a force applied at the rim portion, the force being of such magnitude as not to effect cold binding of the tin at the rim portion; evacuating said container; and heating said container in a bath of molten lead, whereby the cup and closure member are evenly heated and connected and internal stress of the completed capsule is obviated.

32. That method of making an aneroid capsule which comprises the steps or applying solder to the rim of a formed first diaphragm cup; assenibling and placing into an exhaustible container said firs. cup and a second cup adapted to complete said first cup into a capsule, said cups being pressed together by a force applied at the rim portions at said cups, the force being of such magnitude as not to eilect cold binding of. the tin at the rim portion; evacuating said container; and heating said container to a temperature above the melting point of said solder,

whereby said cups are evenly heated and connected and internal stress in the completed cap- -sule is obviated.

said container; heating said container to a temperature above the melting point or said solder; cooling said container; and relieving the vacuum within said container, whereby an evacuated capsule is produced tree from internal stress caused by heating and soldering.

34. That method of making an aneroid capsule which comprises the steps of applying solder to the rim of a formed first diaphragm cup; assembling and placing into an exhaustible container said first cup and a second cup adapted to complete said first cup into a capsule. said cups being pressed together by a force applied at the rim portions at said cups, the force being of such magnitude as not to eil'ect cold binding of the tin at the rim portion; evacuating said container; heating said container in a bath of molten lead to a temperature above the melting point of said solder; cooling said container; and relieving the vacuum within said container, whereby an evacuated capsule is produced tree from internal stress caused by heating and soldering.

PAUL KOLLSMAN. 

